Midget boiler



Jan. 12, 1965 A. B. CHADWICK ETAL 3,165,092

MIDGET BOILER Filed March 50, 1962 T H I /20 5 Sheets-Sheet 1 FZM (QMATTORNEY 5 A. B. CHADWICK ETAL 3,165,092

MIDGET BOILER Filed March 30. 1962 5 Sheets-Sheet 2 A. B. CHADWICK ETALJan. 12, 1965 MIDGET BOILER 5 Sheets-Sheet 5 Filed March 50.- 1962.

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Jan. 12, 1965 A. B. CHADWICK ETAL 3,155,092

MIDGET BOILER Filed March 30, 1962 5 Sheets-Sheet 4 \d az A .I I

5 Sheets-Sheet 5 Jan. 12, 1965 A. B. CHADWICK ETAL MIDGET BOILER FiledMarch 30. 1962 United States Patent 3,165,092 MIDGET BUTLER Abraham B.Chadwick, Jeiiersontown, Arthur 0. joden, Louisville, and Wilson .I.Witten, .Irz, Houston Acres, Ky, assignors to American Radiator &Standard Sanitary Corporation, New York, N.Y., a corporation of DelawareFiled Mar. 30, 1962, Ser. No. 183,863 14 Claims. (Cl. 122214) Thisinvention relates to heating boilers and more par ticularly to midgetsize boilers for heating small homes, buildings and other similarheating requirements.

Various efforts have been made to reduce both the size and the weight ofhome heating boilers and to increase its heat absorbing efiiciency. Theattempts to do this have encountered various problems. For example, whenthe size was reduced the operating efficiency and maintenance of 'theboiler was impaired.

It is therefore an object of this invention to provide a midget sizeboiler which will be lighter in weight and have the equivalent heatingcapacity of heavier and larger size boilers.

Another object of this invention is to provide a boiler wherein theboiler and heat transfer sections are supported independently on legs sothat the combustion chamber may be a separate component which can bereadily attached and removed without disturbing the connections made tothe heating section.

Another object of this invention is to provide a boiler made up of twoseparate and detachable components, namely boiler sections and adetachable suspended combustion chamber section.

A further object of this invention is to provide a selfcontaineddetachable combustion chamber in which the pressure is relieved toreduce the possibility of pulsations therein.

Another object of this invention is to provide standardized top, bottom,and intermediate boiler sections to decrease the number of boilersections to three that have to be stacked to make up different capacityboilers.

A further object of this invention is to provide an arrangement andconstruction of the heat elements wherein all the heat absorbing tubepassage ways are accessible from the top to clean all sides of theelements.

A further object of this invention is to provide heat absorbing elementshaving tubes with fins which extend upwardly and downwardly from thetubes and wherein the tubes are arranged in staggered formation so thata cleaning brush can be inserted at an angle between the staggeredarrangement of heat absorbing tubes, to clean all sides of the tubes.

Another object of this invention is to provide an assembly of flat heatexchange cast iron sections laid one on top of the other, which are allinter-connected by nipples on opposite sides and ends of the cast ironsections.

A further object of this invention is to provide cast iron heatabsorbing sections of a simple design and arrangement wherein thecapacity of a boiler can be readily varied by changing the number ofelements employed and wherein the staggered tube arrangement can beachieved by merely reversing the heating sections.

A further object of this invention is to provide superimposed cast ironsections of a novel and simplified design which will effectivelyseparate air bubbles from the circulating water.

Other objects and features of the invention will appear as thedescription of the particular embodiment selected to illustrate theinvention progresses. In the accompanying drawings, which form a part ofthis specification, like characters of reference have been applied to3,165fi92 Patented Jan. 12, 1965 corresponding parts throughout theseveral views which make up the drawings.

FIGURE 1 is a front elevation, partly in section of the midget boiler.

FIGURE 2 is a partial side elevation taken on line 2-2 of FIGURE 1.

FIGURE 3 is a sectional plan view taken on line 33 of FIGURE 1, showingthe upper cast iron heating section.

FIGURE 4 is a plan view taken on line 44 of FIG- URE 1, showing thelowermost heating section.

FIGURE 5 is a plan view taken on line 55 of FIG- URE 1, showing theconstruction of the intermediate heating sections.

FIGURE 6 is a cross-sectional elevation taken on line 6-6 of FIGURE 5,showing a cross-section of the assembled heating elements.

FIGURE 7 is a cross-sectional side elevation taken on line 7-7 of FIGURE5, showing the construction of the heating tubes.

FIGURE 8 is a cross-sectional elevation taken on line 88 of FIGURE 9,showing the manner in which the legs and outer shell are fastened.

FIGURE 9 is a cross-sectional top elevation taken on line -9 of FIGURE8, showing the construction of the outer shell and the legs, to whichthe outer shell is attached.

FIGURE 10 is a cross-sectional side elevation taken on line 10-10 ofFIGURE 1, showing the adjustable secondary air vent.

FIGURE 11 is a perspective view showing one of the two legs employed forsupporting the assembled boiler sect1on.

Referring to FIGURE 1 of the drawings, the boiler heating sections 10,12, 1 .4, and 16 are bolted together by a pair of diagonally positionedbolts 18, one ofwhich is shown in FIGURE 1. Each of the bolts 18 extendsthrough cast iron flanges 2t) and 24 formed on opposite ends of theupper and lower heat absorbing sections 10 and 16. The opposite ends ofthe bolts 18 are threaded and suitable nuts 26 and 28 are threaded onthe bolts 18 to draw the sections 10, 12, 14, and 16, tightly together.

Nipples 3t), 32, 33, 34, 36 and 38 provide water-tight connectionsbetween each of the heat absorbing sections when the sections are drawntightly together as shown in FIGURE 6. It will be noted that the blindnipple 34 has no passage therethrough to cause the desired circulationof water in the boiler as will be explained more fully. The assembledcast iron elements 19, 12, 14, and 16 are supported on a pair of spacedsheet metal legs 40 shown in FIGURE 1 and FIG- URE 11.

The upper end of the sheet metal legs has a pair of brackets 42 and 44,which are adapted to be bolted fast to the lowermost flange 24 of thelower heating section 10. The lower heating section 10 has flange 24,extending outwardly from opposite sides of the flanges 104, 106. Thisstructural arrangement permits the combustion chamber 54 to be attachedand detached without having to disconnect any other connections to theboiler.

The combustion chamber comprises a sheet metal housing 50, and a castcombustion chamber 54 suspended from the upper end thereof by a lip 56which rests on the sheet metal covering 58 as shown in FIGURE 2. Thecombustion chamber is made of light weight refractory material. A liningof vermiculite 52 is interposed between the cast combustion chamber 54and the housing 50.

The sheet metal covering 58, to which the outer shell is attached, isdrawn upwardly by means of a pair of diagonally and oppositely arrangedbolts 60 and 62,

3 extending through diagonally opposite flanges 64 formed on the lowersection 10. A suitable nut or other threaded device 68 is secured to theunderside of the sheet metal covering 58. In addition, a nut 70 or othersuitable stop is formed on the bolts 69 and 62.

When the bolts 60 and 62 are rotated the nut or stop 7% rotates on topof the diagonally opposite flanges 64 on which they rest, therebycausing the threaded device 68 to ride upwardly on the threaded boltshi) and 62. The shell Stl is thus pulled upwardly against the lowerheatabsorbing section Hi. It will be noted that there is a space 48between the lower shell 5% and the floor 52 which facilitates theremoval of the combustion cham her when the bolts 60 and 62 areloosened.

An outer sheet metal covering, 72, encloses the legs 40 and thecombustion chamber 59. The outer housing 72 is held in place by suitablescrews 74 which extend through suitable corresponding slots formed inthe outer shell 72. The screws 74 are threaded into suitable fianges 76,formed along the length of the legs 40.

A sleeve 73 extends through the cast combustion chamber 54 and throughthe vermiculite liner 52 and the outer shell 59. A similar sized openingis formed in the outer shell housing 80. The head 82 of an oil burnerextends through the shell 78 and causes the burner flame to be projectedinside the combustion chamber 54.

Referring to FIGURE 10, the oil burner head is formed with a secondaryair-adjusting sleeve 86 which serves as an adjustable vent or reliefopening to minimize pulsations within the boiler. Also, since thesecondary air opening extends around the burner tube, any air thatenters the boiler at this point will cool the burner tube. Such air willenter the combustion zone at the optimum point to aid in the combustionprocess. If air were permitted to enter the boiler at other points, itwould have a degrading influence on the combustion process.

The secondary air-adjusting sleeve 86 has a series of holes 88 formedtherein which are in alignment with a similar set of holes, 90, formedin the burner head so that when the inner sleeve 86 is rotated the webportion of the sleeve 86 will control the amount of secondary opening,thus regulating the size of the vent or relief opening. A sheet ofinsulating material 92 is secured to the rotatable sleeve 86 so as toprovide a tight fireproof shield between the removable burner and thesecondary air-adjusting sleeve 86.

Since the boiler is of a small size the combustion chamber 54 will beoperated under higher temperatures than usual. This presented a problemwith res ect to overheating the nozzle and electrodes which was solvedby providing a turbulator having a ceramic ring 54 to effect aturbulation and swirling of the air surrounding the burner nozzle.

The purpose of using ceramic for the turbulator is to keep the peaknozzle temperatures to a minimum. This is accomplished by using amaterial with a high insulating value and a low specific heat. Theturbulator absorbs heat during the firing of the boiler and gives it upafter shut down to its surroundings. During the firing cycle, the nozzleis kept cool by the oil flowing through it and the air flowing aroundit. Peak nozzle temperatures are, therefore, experienced shortly afterburner shut down as the combustion chamber and turbulator give up theirstored heat. By using a ceramic ring, which has a high insulating valueand a low specific heat, the peak nozzle temperature will beconsiderably reduced.

FIGURES 1 to 8 show the manner in which our heating elements areconstructed and assembled together.

The intermediate sections 12 and 14 are of the same construction anddesign and have the interior tubes 96, @8 and 106 equally spaced fromeach other. The side or terminal tube 161 of each section is of the samedimension as the inner tubes 96, 98, and 1th) While the opposite fig.side or terminal tube is approximately 1V2 times the dimension of theinner tubes as, 93 and 1%.

\Vhen this type of section is turned 18% degrees on a vertical axis withrespect to the next adjoining section on which it is superimposed, thetubes of adjoining sections will be staggered with respect to each otheras shown in FIGURE 7. This facilitates heat absorption, cleaning of thelines and the circulation of the heating fluid in the boiler.

Nipples 3t 32, 33 3-2, 36 and 38 provide watertight interconnectionsbetween the circumferential terminal tubes of the superimposed cast ironsections at opposite sides. The cast iron sections are drawn togethertightly by vertical clamp rods diagonally arranged with respect to eachother. The tie rods 13 extends through the flanges 20 and 24 formed inupper section to and the lower section til respectively, as shown inFIGURES l, 3, and 4, and suitable nuts are threaded onto the ends of thetie rods 1% to draw the sections together.

Tubes 96, til have an oval configuration with fins Hi2 extendingupwardly and downwardly from the tubes. An inspection of FIGURE 7indicates how the heating element may be easily cleaned on all sides byinserting a wire brush or suitable member downwardly at an angle betweenthe tubes. It will be evident that cleaning brushes inserted in thismanner are not only able to clean the sides of the tube but they alsoclean the upper and lower fins as they are passed in and out in thismanner. it additional sections are added, such cleaning procedure isstill possible in other words, one section at a time can be added to thesection assembly without interfering with the cleaning process becausethe bottom section it} is sym- 'cal and, therefore, reversible. The topsection remains in the same position and the sections below it arealternately reversed. With this arrangement, the tubes of adjacentsections will always be staggered as shown in FIGURE 7.

Each heating section is surrounded by a peripheral duct fill-N3 havingtapered nipple openings of opposite ends and sides for interconnectingthe superimposed ducts to each other. The lowermost heating element it)is also provided with two flanges 84 and The flange 194 has aconventional circulator pump 1% connected thereto while flange 1% has acorresponding flange lllltl con nected thereto for receiving aconventional drain 112.

The upper section 15 is provided with a tapped opening ii- 5 to whichthe boiler discharge pipe lid is connected as shown in FIGURE 6. Thisopening is positioned on the lower side of the heating element in. Theupper side of the heating element 16 has second tapped opening 113formed therein into which is aded a 12% as U415 shown in FIGURES l and6. A T 124 is connected to the nipple 123i and a relief valve 126 isscrewec. into the E 124. A pipe 123 is connected to the T 124 at one endand at the other end is connected to a suitable expansion tank, notshown.

Since the bottom section 1% is provided with flanged openings til-i,1-596 at two sides, a circular can be attached to either side of theboiler. in FIGURE 1, the circuiator 1&8 is shown on the right hand sideof the boiler with the drain M2 at the left hand side. The position ofthe circulator 1G8 and drain 122 may be reversed so that the circuiator198 is on the left hand side and the drain 112 on the right hand side asviewed in FIGURE 1.

The flow path of water through the boiler is indicated in FIGURE 6. Itwill be noted in the four section boiler of FIGURE 6, that there arethree alternate flow paths. If a three section boiler were used, thenthere would be two alternate flow paths. In either case, the alternateflow paths are equal in length and, therefore, the boiler has a balancedhydraulic circuit and an equal amount of water will flow through each ofthe alternate paths.

If the circulator I03 is mounted on the left hand side of the boilerinstead of the right hand side as shown in FIGURE 1, there will still bethree possible flow paths and they will be similar to those shown inFIGURE 6 since the circulator will force a large portion of water acrossthe bottom section. Any air bubbles that should rise through nipples 38and 36 would encounter blind nipple 34 and thus be directed over tonipple 3t) where the air would rise upwardly into pipe 120.

By positioning a blind nipple 34 immediately in front of the dischargeopening 114 it prevents any water from being drawn or pushed from theheating boiler by the circulating pump 1% before it has passed throughthe heating tubes and been adequately heated. Also, any air bubbles thatshould rise through nipples 38 and 36 would encounter blind nipple 34and thus be directed over to nipple 30 where the air would rise upwardlyinto pipe 120.

In order to determine the condition of the flame inside of thecombustion chamber 54, a suitable inspection tube 122 is mounted throughthe combustion chamber 54 of the vermiculite 52 and the outer shell 50.A suitable cover 125 is provided for covering the inspection tube 122when it is not in use. A suitable support bracket 127 is provided forsupporting the burner 82 by means of a hooked flange 129 extending iromthe burner 82 as shown in FIGURE 2.

A temperature control device 130, a high temperature limit control 132,and a temperature gauge 134 may be provided as required. A canopy 136 isprovided over the top section 16 for conducting the flue gases from theboiler to a flue pipe (not shown).

The invention hereinabove described may, therefore, be varied inconstruction within the scope of the claims, for the particular deviceselected to illustrate the invention is but one of many possibleembodiments of the same. The invention, therefore, is not to berestricted to the precise details of the structure shown and described.

What is claimed is:

l. A boiler comprising top, bottom, and intermediate horizontallyarranged and superimposed heating sections, said heating sections havinga water passage around the periphery thereof, at least some of saidintermediate heating sections, having means defining two generallydiametrically opposed upper openings and two generally diametricallyopposed lower openings communicating with said peripheral passages, apair of first conduit means communicating corresponding upper and loweropenings of the last said superimposed intermediate heating sections toprovide parallel flow paths between the latter, said top heating sectionhaving an air outlet connection, a water outlet connection remote fromsaid air outlet connection, and means defining a bottom opening, andsecond conduit means communicating the last said opening with a topopening of an underlying intermediate heating section, said air outletconnection overlying said second conduit means such that any air andgaseous fluids carried in the water entering said top heating sectionthrough said second conduit means will be expelled through saidoverlying air outlet connection while the water passes through said topheating section to said remote water outlet connection.

2. A boiler comprising top, bottom, and intermediate horizontallyarranged and superimposed heating sections, said heating sections havinga water passage around the periphery thereof, said peripheral waterpassage having a first side portion larger in cross section than asecond opposite side portion such that when superimposed heatingsections are rotated 180 on a vertical axis relative to one another, thesaid first side portion will be opposite the said second side portion,said heating sections having a plurality of substantially equally spacedtransverse Water passages communicating with said peripheral passage andextending generally parallel to said first and second side portions ofsaid peripheral passageway such that the transverse passages ofalternate heating sections are arranged in staggered array, a pair ofgenerally diametrically opposed conduit means communicating theperipheral passages of adjacently arranged heating sections to provideparallel flow paths therebetween, sealing means sealing one of said pairof conduit means between the top heating section and an underlyingintermediate heating section, said top heating section having an airoutlet connection and a water outlet connection, said other of said pairof conduit means between said top heating section and the underlyingintermediate heating section being located remote from said sealingmeans such that air and gaseous fluids carried in the water enteringsaid top heating section through the last said other conduit means willbe expelled through said air outlet connection while the water passesthrough said top heating section to said water outlet connection.

3. A boiler comprising top, bottom, and intermediate horizontallyarranged and superimposed heating sections, said heating sections havinga water passage around the periphery thereof, said heating sectionshaving a plurality of substantially equally spaced transverse waterpassages communicating with said peripheral passage, said peripheralwater passage having a first side portion larger in cross section than asecond side portion such that when superimposed heating sections arerotated on a vertical axis relative to one another, the said first sideportion will be opposite the said second side portion and saidtransverse passages of alternate heating sections will be arranged instaggered array, a pair of generally diametrically opposed conduit meanscommunicating the peripheral passages of each set of adjacently arrangedheating sections to provide parallel flow paths therebetween, sealingmeans sealing one of said pair of conduit means between the top heatingsection and an underlying intermediate heating section, said top heatingsection having a water outlet connection, remote from the other of thelast said pair of conduit means, said bottom heating section having awater inlet connection whereby water entering said bottom heatingsection may flow through said conduit means to any one of saidintermediate heat ing sections in parallel to provide a plurality ofalternate paths of Water flow through the heating sections.

4. A boiler as set forth in claim 3 wherein said transverse heatingpassages have a generally oval cross-sectional configuration with themajor axis thereof vertically disposed.

5. A boiler as set forth in claim 4 wherein said transverse passages ofsaid intermediate heating sections are provided with top and bottomgenerally flat elongated fins in line with said major axes.

6. A boiler as set forth in claim 3 wherein each of said pair of conduitmeans are axially aligned with one another.

7. A boiler as set forth in claim 3 wherein said water inlet connectionleads from the side walls of said bottom heating section such that waterintroduced therethrough has a horizontally directed component tending tocause the water to flow through the water passages of said bottomheating section.

8. A boiler comprising top, bottom, and intermediate horizontallyarranged and superimposed heating sections, said heating sections havinga water passage around the periphery thereof, said intermediate sectionhaving means defining upper and lower openings communicating with saidperipheral passages, a pair of generally diametrically opposed firstconduit means communicating corresponding upper and lower openings ofsuperimposed intermediate heating sections to provide parallel flowpaths therebetween, said bottom heating section having means definingupper openings, a pair of second conduit means comrnunicating the lastsaid openings with the bottom openings of a superimposed intermediateheating section, said bottom heating section having a pair of inletconnections communicating with its peripheral passage such that inletwater may be selectively introduced into either one of said inletconnections, said top heating section having an air outlet connection, awater outlet connection, and

means defining a bottom opening, and third conduit means communicatingthe last said opening with a top opening of an underlying intermediateheating section, said air outlet connection underlying said thirdconduit means to receive rising air and gaseous fluids carried in theWater entering said top heating section through said third conduitmeans.

9. A boiler as set forth in claim 8 wherein said pair of inletconnections are horizontally opposed from one another to thereby provideselectively a right hand or left hand water inlet connection.

10, A boiler as set forth in claim 8 wherein each of said pair of inletconnections is provided with means adapted to receive selectively awater circulating pump or a drain connection.

11. A boiler comprising top, bottom, and intermediate horifzontally'arranged and superimposed heating sections, said heating sections havinga water passage around the periphery thereof, said peripheral Waterpassage having a first side portion larger in cross section than asecond opposite side portion such that when superimposed heatingsections are rotated 180 on a vertical axis relative to one another, thesaid first side portion will be opposite the said second side portion,said intermediate heating section having means defining upper and loweropenings communicating with said peripheral passage, a pair of generallydiametrically opposed first conduit means cornmunicatingcorrespondingupper and lower openings of superimposed intermediate heating sectionsto provide parallel fiow paths therebetween, said bottom heating sectionhaving a pair of opposed inlet connections communicating with saidperpheral passage such that inlet water may be selectively introducedinto either of said inlet connections, said bottom heating sectionhaving means defining upper openings, a pair of second conduit meansconnecting the last said openings with the bottom openings of asuperimposed intermediate heating section, said top heating sectionhaving an air outlet connection, a Water outlet connection, and meansdefining a bottom opening, and third conduit means connecting the lastsaid opening with a top opening of an underlying intermediate heatingsection, said air outlet connection being arranged closer to said thirdconduit means than said water outlet connection such that any air andgaseous fluid carried in the Water entering said top heating sectionthrough said such third conduit means may be expelled through such airoutlet connection while the Water passes through said top heatingsection to said water outlet connection.

12. A boiler as set forth in claim 11 wherein said air outlet connectionis in the top wall of said top heating section and said Water outletconnection is in a side wall of said top heating section.

13. A boiler comprising top, bottom, and intermediate horizontallyarranged and superimposed heating sections, each of said heatingsections having a water passage around the periphery thereof and aplurality of spaced transverse water passages, said peripheral waterpassages having one side portion larger in cross section than anopposite side portion such that each heating section may be stacked inrespect to the next higher and lower heating section by being reversedby rotation of 180 on a vertical axis so that said heating sections willbe staggered Withrespect to each other, at least some of saidintermediate heating sections having means defining two generallydiametrically opposed upper openings and two underlying generallydiametrically opposed lower openings, conduit means communicating saidupper and lower openings to provide parallel flow paths between saidinter mediate heating sections, said bottom heating section having aninlet on the opposite sides thereof adapted to interchangeably receive acirculating pump on one side and a drain on the opposite side, said topheating section having a Water outlet connection in a sidewall thereof,said top heating section having an air outlet connection in the top wallthereof on the side or" the top heating section opposite from said Wateroutlet connection, such that any air and gaseous fluids carried in theWater entering said top heating section will be expelled through saidair outlet connection while the water passes through said top heatingsection to said water outlet connection.

14. A boiler comprising top, bottom, and intermediate horizontallyarranged and superimposed heating sections, each of said sections havinga water passage around the periphery thereof, a plurality of spacedtransverse water passages connected at either end to said peripheralwater passage, said peripheral water passage having a first side portionlarger in cross section than a second opposite side portion such thatwhen superimposed sections are rotated on a vertical axis relative toone another, the said first side portion will be opposite the saidsecond side portion, said peripheral Water passage also having theopposite side portions of substantially equal cross section, at leastsome of saic intermediate heating sections having means defining twogenerally diameti sally opposed upper openings and two underlyinggenerally diametrically opposed lower openings in each of said otheropposite side portions of said peripheral passage, a pair of firstconduit means in said upper and lower openings interconnecting adjacen-iv arranged intermediate heating sections to provide parallel flowpaths between the latter, said bottom heating section having an inletconnection in each of said other opposite side portions of saidperipheral passage, said bottom heating section having upper openingsadapted to receive second conduit means for fluid connection to asuperimposed intermediate heating section, said top heating sectionhaving an air outlet connection in the top wall of one of said sideportions of its peripheral passageway and a water outlet connection inan opposite side portion of its peripheral passageway, said top heatingsection having bottom openings, third conduit means connecting one ofsaid bottom openi is of the top heating section with an underlyingintermediate heating section, and means preventing fluid d W betweenanother of said bottom openings of the top heating section with anunderlying intermediate heating section such that wate' entering the topheath: section will pass through said third conduit means ad acent tieair outlet connection in the top heating section before passing throughthe top heating section and exiting through said Water outletconnection.

References Cited in the file of this patent UNlTED STATES PATENTS

1. A BOILER COMPRISING TOP, BOTTOM AND INTERMEDIATE HORIZONTALLYARRANGED AND SUPERIMPOSED HEATING SECTIONS, SAID HEATING SECTIONS HAVINGA WATER PASSAGE AROUND THE PERIPHERY THEREOF, AT LEAST SOME OF SAIDINTERMEDIATE HEATING SECTIONS, HAVING MEANS DEFINING TWO GENERALLYDIAMETRICALLY OPPOSED UPPER OPENINGS AND TWO GENERALLY DIAMETRICALLYOPPOSED LOWER OPENINGS COMMUNICATING WITH SAID PERIPHERAL PASSAGES, APAIR OF FIRST CONDUIT MEANS COMMUNICATING CORRESPONDING UPPER AND LOWEROPENINGS OF THE LAST SAID SUPERIMPOSED INTERMEDIATE HEATING SECTIONS TOPROVIDE PARALLEL FLOW PATHS BETWEEN THE LATTER, SAID TOP HEATING HAVINGAN AIR OUTLET CONNECTION, A WATER OUTLET CONNECTION REMOTE FROM SAID AIROUTLET CONNECTION, AND MEANS DEFINING A BOTTOM OPENING, AND SECONDCONDUIT MEANS COMMUNICATING THE LAST SAID OPENING WITH A TOP OPENING OFAN UNDERLYING INTERMEDIATE HEATING SECTION, SAID AIR OUTLET CONNECTIONOVERLYING SAID